The present invention relates to a measuring device for measuring components of a crop material.
Publication EP 0 843 959 makes known an agricultural working machine designed as a forage harvester, which includes a measuring device in its upper discharge chute for detecting parameters of a crop-material flow passing through the forage harvester. The measuring device detects the crop-material properties using a microwave sensor. Special algorithms are provided that eliminate influencing quantities that may occur, or at least reduce their effect on the crop-material parameters to be detected. Due to the enormous amount of information contained in the change—caused by material flow—in the electrical field of the microwaves, it is possible—using suitable analytical software—to detect, e.g., the moisture content of the crop material flowing through the agricultural working machine. In one variant of the embodiment, it is also provided—in order to reduce possible sources of error—to also take the temperature value of the crop material into account in the analysis of the microwave signals, the temperature value being registered using separate temperature sensors.
Even though systems of this type are capable—when suitable analytical software is used—of determining a large number of crop-material parameters, microwave sensors have the disadvantage in particular that integrating them in agricultural working machines is very cost-intensive, which makes them unsuitable for widespread agricultural use, e.g., in drawn agricultural working machines. This is due, in particular, to the fact that a large number of technological conditions must be created so that the microwave signals may detect a crop-material flow with minimal interference and so that machine or crop-material-related interferences may be largely compensated for.
For this reason, e.g., a sensor system is disclosed in EP 0 931 446 that ascertains—using two electrodes—the conductance of a crop-material flow that passes by the sensor and ultimately uses the conductance that was ascertained to derive a value for the moisture content. The conductance sensor itself is composed of a peg-shaped electrode and a circular electrode, and it may be located at any point in the upper discharge chute—through which the crop material flows—of a self-propelled forage harvester. The position of the conductance sensor in the agricultural working machine is selected such that the sensor device delivers reliable measured results and is protected from wear to the greatest extent possible. A system of this type has the advantage in particular that a sensing device for parameters of a material flow passing through an agricultural working machine is created with little technical outlay and, therefore, minimal costs.
A significant disadvantage of designs of this type, however, is that an optimal position of a measuring device of this type is determined mainly by the moving behavior of the crop material in the agricultural working machine, and it may change considerably depending on the type of crop, the kinematic parameters of the various working devices, and the moisture content of the crop material. This means that it is not entirely possible to assume what a universally-valid, optimal position of the material-detection device is. As a result, the crop-material parameters detected with a device of this type does not deliver reliable measurement results in every case. Given that the moisture content has a significant influence on the determination of the throughout of crop material passing through an agricultural machine, it is very significant that the detection of the crop-material moisture detected using measurement technology deliver precise values during the working operation of the agricultural machine.